Abstract: When an elastic panel boundary is subjected to indentations by relatively rigid, square-ended uniform punches, a singular stress field and K-dominant region should be arisen adjacent to the punch edges. The stress intensity factor indicates that the stress intensity degree of the stress field is similar to the mode I crack, so K is an important parameter for boundary fracture cracked under indentations. In present article, a method to formulize the SIF for the singular stress fields induced by double-side indentations is proposed by the basis of the conservation J-integral, some numerical examples are also given.